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segunda-feira, 19 de março de 2012

New rabies virus identified

14 MAR, 2012
by Michael Regnier

African civets are nocturnal, cat-like animals.

A case of a child being bitten by a rabid civet has led researchers to a new species of virus that causes rabies. The new species is sufficiently different from other rabies viruses that it is not yet clear whether current vaccines are effective against it.

On Monday 11 May 2009, rangers in Serengeti National Park, Tanzania, killed an African civet suspected of having rabies. The civet had bitten a child on the leg in an unprovoked attack, which brought the animal to the attention of the authorities. The child was treated and given a post-exposure rabies vaccine, and is doing well. It was later confirmed that the civet did have rabies, but it was caused by a virus related to, yet significantly different from, previously known rabies viruses.

Rabies is caused by various species of Lyssavirus. By far the most common is Rabies virus itself, which can infect all mammals and is endemic particularly among dogs in many countries around the world, including Tanzania. Rabies had not been detected in the Serengeti area since 2000, however, thanks to mass vaccination campaigns for dogs in local villages. The case of the civet, therefore, was a surprise and at first implied a breach of the programme to keep the Serengeti free of rabies.

Research published online last month showed that the civet was infected not with Rabies virus, however, but a new type of lyssavirus most closely related to one found in bats in Eastern Europe. The new virus has been named Ikoma lyssavirus after Ikoma ward in Serengeti National Park where the civet was killed. It is possible the civet was infected from a bat carrying Ikoma lyssavirus but the natural host, distribution and prevalence of the new virus are impossible to determine until further studies provide more data.

From the Animal Health and Veterinary Laboratories Agency (AHVLA), Professor Anthony Fooks, a senior author of the study describing the new virus, said: “Due to the highly divergent nature of this novel virus it is not clear whether current human and animal vaccines will confer protective immunity and are effective following an exposure.”

Professor Sarah Cleaveland of the University of Glasgow is another author on the paper. She said Ikoma lyssavirus is “unlikely to pose a threat to humans on the scale of that of dog rabies. However, this research highlights the need for vigilance and maintaining good levels of surveillance.”

The Wellcome Trust funded the rabies surveillance project in Tanzania. Other funders of the work in Tanzania were Lincoln Park Zoo (Chicago), UBS Optimus Foundation and the Medical Research Council.

The research characterising the new virus was led by scientists at the University of Glasgow and the AHVLA, and was funded by the UK’s Department for Environment, Food and Rural Affairs, the European Union, the US Department of Homeland Security and the Fogarty International Center.

“The study also demonstrates how powerful new genetic tools are revealing the complexity of emerging viruses at the wildlife-human interface,” added Professor Cleaveland.